Spring



SPRING Filed April 2. 1925 s Sheets-Sheet? 1 ATTORNEY.

' F. J. SMITH Fi-led Avril 2, 1925 SPRING 5 Shoots-Sheet 2 INVENTOR.

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- 1,62 561 1927' F. J. SMITH SPRING Filed April 2. 1925 I 5 ShutkSheotQ 3 INVENTOR.

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A TTORNEY.

May 10. 1921. 1,628,561 r J SMITH A sauna Filed Aprn z, 1925- 5 Sheets-Sheet 4 I N V EN TOR.

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ATTORNEY.

1,628,561 F. J. SMITH SPRING Filed April 2, 1925 5 Shouts-Shut 5 INVENTOR.

ATTORNEY.

Patented May 10, 1927.

FRANCIS JOSEPH SMITH, 0F GARY, INDIANA.

SPRING.

Application filed April 2, 1925.

This invention relates to suspension springs for motor vehicles and the like constituting improvements in my co-pending application, Serial No. 680,260, filed December 12, 1923, and which ap )lication has matured into United States Fatent No. 1,577 ,7 67 and has for an object the promotion of a novel and improved spring of great flexibility and strength for the support of the Weight of vehicles and the compensation for shocks and vibrations incident to the travel over rough roads.

()ne of the objects of my invention is to provide a leaf spring of a plurality of superimposed connected leavesof varying length, and what I term as a variable strength spring. functioning as though it were always carrying a full load. It has been found that the great difficulty involved in suspension spring design is due to the varyin"; load and the unsprung weight. Both of these make intermittent calls for. great strength. The variable strength spring hereinafter to be described is designed to compensate for the stress and strain placed on the spring and affording the greatest flexibility at all times.

To enable others skilled in the art to fully comprehend the underlying features of my invention, that they embody the same in the various modifications in structure and relation contemplated, drawings depicting a preferred form have been annexed as a part of this disclosure and in such drawings, similar reference characters denote corresponding parts throughout all the views, of which,

Figure l is aview showing the application of my invention to the axle and frame of a motor vehicle.

Figure 2 is a view of the spring detached.

Figure 3 is a disassembled view.

Figure 4 is a sectional view through the spring showing 28 leaves.

Figure 5 is a view of a suspension spring constructed in accordance with my design, for the front end of the chassis.

Figure 6 is a detached view.

Figure 7 is a disassembled view.

Figure 8 is a view showing the spring attached to a fixed and a movable point, known as the Hotchkiss drive.

Figure 9 is a view showing the full elliptical type of spring on the front end of the chassis.

' Figure 10 is a disassembled view.

Figure 11 is a view of a spring having a fixed and a movable end, and being somevscull-circular and evenly distributed. (on- Serial No. 20,210.

what less resilient than the type of spring shown by Figures 1 and 5.

- a I Figure 12 is a simdar view to that shown by Figure '11. Figure 13 is a type of spring shown by F1 gure 11, when detached.

Figure 14 is a view showing the spring, as shownin Figure 13, disassembled.

Figure 15 is a seinicantilever type of spring showing a modified form of the invention, for the rear end of the chassis.

Figure 16 shows the spring of Figure 15 disassembled. i I

Figure 17 is a sectional view through the spring shown by Figure 1.5. 1

F1gurel8 is a sen'iicantilever for the rear end of the chassis.

is generally recognized that the stress and strain on any single spring is not generally distributed throughout its entire length but rather, is concentrated near a point of support, which may be considered on a vertical line drawn through the axle 53, as shown by Figure 1, to which the spring is attached by the U-bolt 6 and the connecting strap 7, fastened by the nuts 8. This application embodies the practice of obtainmg a more even distribution of the strain throughout the entire length of the leaves. It is based on the fact that although flexure of any spring constructed. of a plurality of superimposed, arched leaves, regularly graduated, is concentrated near thepoint ofsupport, this rule will cease to operate as soon as the flexure reaches a point considered on a horizontal line drawn throi'lgh the axle and the loaded. ends, or in other words. on a line at right angles to the vertical. Thus, if any group of superimposeiil. graduated, flat leaf springs carried the load at their ends, as for instance by the links 9, 1.0, which are pivoted as at 11, 12, to the cliassisl -i, the flexure of the leaves would be substantially sequently, if the spring is designed for the chassis so that at least one'half of thetotal. flexure of the spring takes place after the horizontal is reached, I can increase the safe load on such a spring at least 50%. I construct the spring as shown by Figures 1 to 3 inclusive by iiroviding a top connecting spring 14, terminating in the eyes if) whereby t-he spring may be attached to the links as shown and thus bear the entire weight 0 of the load, thus connected to the axle of the wheel by the U-bolt or strap (3 above referred to. It will be observed that the spring 14: is flexed slightly in the reverse direction to the superimposed leaves 15, while certain ot the leaves are connected to the spring 14 by the strap 16, the shorter or top leaves are connected by the strap (3. In Figure 4, I have shown the leaves 16 as consisting of no less than 28 superimposed leaves which give the most efficient result in a'spring construction of the above character. 7 7

In actual practice, the leaf 14: is made of 1 inch spring steel. The superimposed leaves 15 are preferably constructed of inch spring steel. The top spring has the strength of substantially 7:3 pound per inch of llexure whereas the superimposed leaves have a tlexure of substantially 25 pounds perinch. As shown by Figure 2, the top and superimposed leaves are under a strain of substantially 500 pounds.

In Figure 5 is shown a front spring. One end of the spring is preferably connected to a fixed pivot 18 of. the chassis 123 whereas the opposite end 19 ot the spring is connected to a movable or pivoted link 20 suspended at 21. The spring proper is connected by the U-bolt or strap to the I beam 23 of the chassis. The top main leaf 17 is therefore to be regarded as the reverse stress or strength. The dead weight of the chassis is supported by the superimposed leaves, which are as flexible a group as is practicable.

In Figure 8 of drawing the superimposed leaves 25 and the main top leat 26 are similarly connected by the U-shaped strap 27 encircling the axle and connected at the top by the plate and the nut, used in the same manner above described. The main leaf also terminates in eyes connected to a movable link 28 and a fixed support 29 and I have found that a spring of this type produces a forward thrustin thecar wheel, whereas a decrease or flexure in the superimposed leaves and thetop connecting leaf produces a backward thrust. From the spring constructions in present use, a thrust is produced in opposite direction.

In Figure 9, I have shown the principle of the variable strength spring applied to a full elliptical spring in which the intermediate main leaves 30, 31, are connected to the superimposed leaves 52 at the top'and the superimposed leaves 3 3 at the bottom. In this form of spring, the central leaves 30, 31, are under no strain when connected to the chassis of the vehicle and the front axle as shown by Figure 9 ot the drawings.

. In Figure 11, I have shown the spring consisting of the superimposed leaves connected to the axle, the ends of the main leaves connected to a fixed pivot 3a and the pivoted link This construction also permits of a horizontal thrust whereas in Figme 13, one end of the spring is connected to the end 16 of the chassis and the opposite end to the link 57 attached. to the chassis.

In Figures 13) and 1.4, I have shown the spring assembled and disassembled, there being provided a central main l art 335, the top leat :59, slightly bowed or llexed in the direction ot the superimposed leaves 40. The leaf 18 terminates in the eyes ll. It will be observed that the superimposed leaves 10 and the short leaf 39 are connected by the straps 42 so that they are disposed in substantial parallelism with the central leat 38.

In Figures 15 to 18 inclusive, I have shown a modified form of the invention where the spring connected to the chassis 123 and the axle l-l ot the vehicle, the superimposed leaves 415 being of decreased length and connected to the bottom main lent do by the straps =1? and U-bolt 48. In Figure is, the same type of spring is connected to the I beam 49 of the chassis, bein hown,

applied. to the front wheel ot the motor vchicle. As in the previously described form oi the invention, the bottom leaf 4-0 is oi? greater strength than the superimposial leaves.

It will be noted throughout all the drawings that show the dilierent methods of attaching the springs to the chassis, that all increases in the amount of flexure shown. will produce a slight forward thrust of the wheel along a horizontal plane and that all decreases in the amount of llexurc shown. will produce a slight barkuun'd thrust alone a horizontal plane. All methods of spring design and attachment in use today, pro duce horizontal thrusts in the opposite directions.

The drawings also show that all of the main leaves are shaped exactly the same atte attachment to the vehicle, as they were before assembly. Thus, leaf 1-1 in Figure 3 has the same shape in Figure 1: lead '17 in Figure 7 has the sanusha pc in Figure 5: leaves 30 and 31 in Figure 9 have the same shape in Figure 10; lea l l!) in Figure ll has the same shape in Figure ll: leal lo in Figure 1.6 has the same shape inFigurc lfl. Therefore, in these instances, the load represented by the empty vehicle is being supported entirely by the groups ol light leave which are as flexible -as it is practicable to build. he whole group oi leaves In in Figure 3, supports only 23 pounds per inrh of tlexure, being made of inch spring steel. While the leaf 1401? l. 'gure 3 supports 72 pounds per inch o'l liexur being made oi M inch spring steel. The shape that the heavy leaf is given is governed in each instance, by the shape that the grmsp of light leaves alone, is going to assume "when the weight ot the empty vehicle is applied to it.

The universal pra tice oi urchins the leaves of a spring, causes the strain rcsuhing from load to be concentrated within about one third of their length. Vhereas, it any group of graduated leaves be left llat, the flexure resulting from load will be evenly distributed and circular. A. sprin in which the strain is evenly distributec, will safely carry 100% more weight than one made of well arched leaves. Figures 1.5, 16 and 18 show a design using principally fiat leaves.

Tllhroughout this specification, the endeavor has been to describe a laminated spring constructed of very light material arranged in cooperation with a small amount of very heavy material, so that a strain relation will exist between the two materials, that will always force the light material to be strained beyond a certain point before the heavy material can begin to be strained at all, in that given direction. The certain point of strain in the light leaves, being about equal to the strain that would be produccd in the light leaves alone, by the ap' plication to the light leaves alone, of a weight about equal to the sprung weight of the vehicle.

Vhile I have illustrated and described my invention with some degree of particularity, I realize that in practice various alterations therein may be made. I therefore rcserve the right and privilege of changing the form of the details of construction, or otherwise altering the arrangement of the correlated parts, without departing from the spirit of the invention or the scope of the appended claims.

Having shown and described my invention, what I claim as new and desire to secure by United States Letters Patent is:-

l. A suspension spring comprising a main leaf of substantially heavy material, and a. graduated group of leavesof light: n'iaterial, the said heavy main leaf being given the same shape as would be assumed by the roup of light leaves after they alone had 'een placed under a weight substantially equal to the sprung weight of the vehicle for which it is designed, and means for assembling these leaves in cooperation with each other.

2. A suspension spring con'iprising a group of light leaves. a heavy main leaf maintained in a position of freedom from all strain resulting from the dead weight of the vehicle by said group of light leaves graduated in length, the said group of light leaves having been urged past that point of flexure at which fibre strain begins to be evenl distributed throughout the length of all 0 the leaves by the dead weight of the vehicle itself.

3. A suspension. spring comprising an arched main leaf terminating in eyes and adapted to be attached at. its ends to the chassis of a vehicle, a plu 'ality of superimposed leaves of gradually decreased length bowed outwardly and in the reverse direction to the main leaf, the strength of the main leaf being substantially greaterthan the superimposed leaves and means for connecting said main leaf and superimposed leaves.

In testimony whereof I afiix my signature.

FRANCIS J. SMITH. [1,. s.] 

